The present invention relates to the manufacture of semiconductor devices. More particularly, the present invention relates to improved techniques for dielectric etching and resist stripping.
In the manufacture of certain types of semiconductor devices, dielectric layers may be etched using a plasma etching system. Such plasma etching systems may be high density plasma systems, such as inductive or ECR systems, or medium density plasma systems, such as a capacitive system. The high density plasma etchers dissociate gases so well that by providing oxygen to the chamber the chamber walls are cleaned. This cleaning may be caused by the heat generated by the plasma, UV radiation generated by the plasma, and a lot of dissociation caused by the plasma.
Medium density plasma etching systems, such as capacitive plasma systems, may be used for oxide etching. In such medium density plasma etching systems a polymer forming chemistry is typically employed. Such medium density plasma etching systems typically cause polymer deposits to form on the chamber wall. Such systems usually allow the polymer deposits to build on the chamber walls and then are wet cleaned to remove the polymer deposits. The wet cleaning is typically required in medium density plasma systems, since such systems typically do not have sufficient dissociation, and sufficient plasma energy contacting the walls to perform a satisfactory polymer cleaning. When the chamber walls are only partially cleaned and polymer is not satisfactorily removed, sometimes new polymer does not sufficiently stick to the chamber wall possibly creating particles, which could be an added source of contamination.
Plasma etching systems that use plasma confinement, such as the device disclosed in U.S. Pat. No. 5,534,751 by Lenz et al., entitled xe2x80x9cPlasma Etching Apparatus Utilizing Plasma Confinementxe2x80x9d, issued Jul. 9, 1996, generally confine a plasma within a confinement ring that keeps the plasma in a confined area away from the chamber wall. Keeping the plasma in a confined area generally provides a dense enough and hot enough plasma adjacent to the confinement ring to clean the confinement ring.
It is known to provide CVD devices with remote plasma sources, which are typically used to clean the CVD chamber. Typically such plasma devices use a fluorine chemistry. Such CVD devices are used for vapor deposition.
It is known to use a remote plasma source in a strip chamber, which typically uses the remotely generated plasma to strip an etch mask.
In view of the foregoing, it would be desirable in medium density plasma systems, where a plasma of a density that is insufficient to sufficiently clean the chamber wall is generated by the medium density plasma systems, to provide a means for providing a plasma to sufficiently clean the chamber walls.
The invention relates, in one embodiment, to a medium density dielectric plasma etching system with an additional remote plasma source to provide a cleaning of the plasma system and to possibly allow stripping within the etching system.
The invention relates, in a second embodiment, to a medium density plasma system with an additional remote plasma source and with a heater for heating the walls of the chamber to allow cleaning of the chamber wall.
The invention relates, in a third embodiment, to a confined medium density plasma system with an additional remote plasma source to increase the rate of in situ stripping.